Well, in these fanfictions, the theme of discovery is quite common. The reader discovers not only the tentacles but also new aspects of themselves. Fear is another theme that frequently shows up. Since tentacles can be quite an unusual and potentially scary concept, the reader's fear and how they overcome it (or not) is often explored. And of course, there's the theme of the extraordinary. These stories are about experiencing something that is far from ordinary, and the tentacles are a big part of that extraordinariness.
A common theme is the exploration of the unknown. The tentacles often represent something strange and different from the reader's normal world, so it's about delving into that mystery. Another theme is connection, like how the reader forms a relationship, whether it be friendly or something more, with the tentacle - like entities.
One common theme is discovery. The reader character often discovers the existence of tentacles in a new and unexpected world. Another theme is acceptance. They have to accept the presence and nature of these tentacles. For example, in some stories, the tentacles might be part of a strange but beautiful ecosystem.
Relationship building is also quite prevalent. It could be a friendship or a more complex bond between the male reader and the tentacle characters. There is also the theme of mystery, as the tentacle - related elements usually bring an air of the unknown. For example, in many stories, the origin of the tentacles or their purpose in the world is something the male reader has to figure out.
A sense of belonging is another big theme. The reader, who may feel like an outsider in the real world, finds a place where they belong among the mutants. There are also themes related to fighting for justice, just like the X - Men do in the original stories.
Another common element is the relationship between the male reader and the tentacles. It could be a friendly one, where they help each other, or a more complex relationship where the male reader has to figure out how to coexist. Some fanfics play with the idea of the tentacles having a sort of sentience.
One common theme is adventure. Since Chekov is part of the Star Trek universe, many fanfictions involve the reader going on adventures with him through space, exploring new planets and facing various challenges.
Love and sacrifice are also very common. The reader might fall in love with Vergil and be willing to sacrifice for him, or vice versa. In some fanfictions, there is also the theme of discovery. The reader discovers new sides of Vergil that no one else has seen, which deepens their relationship.
One common theme is adventure. Since boboiboy is often involved in battles and saving the world, the reader character gets to be part of those exciting adventures in the fanfiction.
One common theme is growth. Both Armin and the reader often grow as individuals while their relationship also evolves. For example, they might learn to be braver in the face of danger.
One common theme is friendship. Since Fluttershy is a character known for her gentle and friendly nature, many fanfictions focus on building a strong friendship between her and the reader. Another theme is personal growth. The reader often helps Fluttershy overcome her shyness, and in the process, both characters grow.
A common theme is the exploration of Nico's character. Fanfiction writers often dig deep into Nico's personality, his insecurities, his strengths. And the reader character is usually the catalyst for this exploration. Another theme is the power of connection. Whether it's a romantic or platonic connection, it's shown to be very powerful. For instance, in some fanfictions, the connection between Nico and the reader is what saves them from a dangerous situation.